Devices and methods for the improvement of ectatic and irregular corneal disorders

Abstract

Disclosed are devices and methods for the improvement of ectatic keratopathy using corneal augmentations derived from corneal tissue. The shape of the augmentation is determined using data obtained from computerized corneal topography and tomography-based mapping of the patient's cornea. Factors considered include maximum corneal curvature measurements and specific iso-deviation contours. In one embodiment, the augmentation is a corneal inlay intended for insertion into an intrastromal pocket. In a further embodiment, the augmentation is a corneal onlay intended to be positioned over an area of ​​the cornea from which an epithelial layer has been removed. The corneal onlay is held in place until the epithelial layer regrows over the augmentation. In a further embodiment, the inlay or onlay augmentation is followed by further reshaping after augmentation of the corneal augmentation. In one embodiment, this further reshaping is photorefractive keratectomy (PRK) surgery.

Description

[Technical field]

[0001] Inventors: Peter S. Hersh, Steven A. Greenstein, and John D. Gelles

[0002] (CROSS REFERENCE TO RELATED APPLICATIONS) This is a PCT patent application that claims priority to U.S. Provisional Patent Application No. 63 / 225,484, filed July 24, 2021, and U.S. Patent Application No. 17 / 528,484, filed November 17, 2021, the contents of both of which are incorporated by reference in their entireties herein.

[0003] (Technical field) The present invention relates to medical devices and methods for the improvement of ectatic and irregular corneal disorders, and more particularly to the production and / or use of corneal augmentations, which may be used as either inlays or onlays to improve ectatic corneal disorders, such as, but not limited to, keratoconus. [Background technology]

[0004] (Background technology) Corneal ectasia is the result of corneal thinning and subsequent distortion. This distortion alters the normal optical anatomy of the cornea and reduces visual acuity. Corneal ectasia can have several causes and can manifest as pathologies such as, but not limited to, keratoconus, persic corneal degeneration, and keratoglobus. Corneal ectasia can also be iatrogenic in nature and can result from various surgeries such as, but not limited to, laser-assisted epikeratomileusis (LASIK), small incision lenticule extraction (SMILE), and photorefractive keratectomy (PRK).

[0005] The most common natural manifestation of corneal ectasia is keratoconus, a condition that occurs in approximately 1 in 2,000 individuals. It is an asymmetric corneal ectasia disorder characterized by progressive corneal protrusion and thinning, which typically results in irregular astigmatism and impaired visual function. In particular, the normally dome- or spherically shaped cornea becomes distorted, resulting in the formation of a cone-shaped ridge. This cone-shaped ridge typically adversely affects vision.

[0006] Devices and methods for improving corneal ectasia depend on the type and severity of the condition and include treatments such as, but not limited to, contact lenses, intracorneal implants, cross-linking, and corneal transplants.

[0007] Intracorneal implants include, but are not limited to, intrastromal corneal ring segments (ICRS) made from materials such as PMMA. In the United States, they are often referred to as Intacs®, which is the trade name for a device produced by Addition Technology, Inc. of Lombard, Illinois, a subsidiary of AJL Ophthalmic, a Spanish company headquartered in Minano, Alva, Spain. One drawback of such inserts is that almost all suitable materials have a refractive index significantly higher than the refractive index of the cornea's stromal collagen, 1.376. This mismatch can result in undesirable reflective surfaces that can interfere with vision. Additional complications that can result from a lack of biocompatibility include stromal dissolution and ring segment protrusion. Furthermore, commercially available ring segments are currently fixed in arc length, width, inner and outer diameters. The only variable is thickness, and therefore the device cannot be customized to any great degree of precision. Summary of the Invention [Means for solving the problem]

[0008] DISCLOSURE OF THEINVENTION An invention device and method for the improvement of ectatic corneal disorders is disclosed. Corneal ectatic disorders are the result of thinning of the cornea, which may become distorted and therefore may adversely affect the patient's vision. They include diagnoses such as forms of astigmatism, including, but not limited to, keratoglobus, persicoid corneal degeneration, keratoconus, and irregular astigmatism.

[0009] As part of the assessment of the severity of the patient's disorder, one or more corneal maps of the patient's cornea may be obtained. These maps may be, but are not limited to, tomographic, topographic, or elevation maps, or some combination thereof. These maps may be used, for example, to locate the cone of keratoconus and to quantify the maximum keratometric value of the patient's cornea.

[0010] In a preferred embodiment, corneal maps of a patient exhibiting an ectatic or irregular disorder may be generated using methods such as, but not limited to, computerized corneal topography and corneal tomography. Information derived from these maps, such as, but not limited to, maximum corneal curvature measurements and various iso-deviation contours, may then be used to calculate an appropriate three-dimensional shape of a corneal augmentation suitable for improving the ectatic or irregular disorder. The ideal shape of the corneal augmentation may be, for example, one that restores the patient's cornea to an ideal cornea, i.e., a portion of a spheroid, with a refractive power in the range of 30-50 diopters, with an eccentricity in the range of -2 to +2.

[0011] The corneal template may be obtained, for example, as a corneal autograft, a corneal allograft, a corneal xenograft, or as manufactured corneal tissue, or some combination thereof.

[0012] The present corneal template may be treated for several purposes, including but not limited to, to improve its biocompatibility, to maintain its clarity, and to increase its biomechanical strength.

[0013] The corneal template can be formed into a device that is a corneal augmentation having a desired three-dimensional shape, which may be accomplished using, for example, computer-guided femtosecond or excimer lasers, or a combination thereof.

[0014] The corneal augmentation can then be used to augment the cornea either as an inlay or as an overlay.

[0015] When the corneal augmentation is an inlay, the cornea of ​​a patient exhibiting an ectatic defect can be prepared to receive the corneal augmentation by creating an intracorneal cavity, for example, using a femtosecond laser. The intracorneal cavity can be a space such as, but not limited to, a channel or pocket with a suitable opening for insertion of the augmentation. The corneal augmentation can then be inserted into the intracorneal cavity, thereby augmenting the patient's cornea and improving the shape and optical performance of the patient's cornea, thereby improving the patient's vision.

[0016] When the corneal augmentation is an onlay, the cornea of ​​a patient exhibiting an ectatic defect may first be prepared by removing an area of ​​epithelial tissue from the cornea. A surface chamfer may then be created on the periphery of the area of ​​removed epithelial tissue, for example, using a femtosecond laser. The corneal augmentation may then be augmented onto the patient's cornea and initially held in place, for example, by inserting a tapered or chamfered edge of the corneal augmentation into the chamfer of the epithelial tissue. This may keep the onlay in place while the epithelial tissue grows over it. Surgical adhesive or sutures may also or instead be used for this temporary retention. Epithelial regrowth may take several days to a week, during which time the patient's cornea may be protected by a surgical contact lens. Once in place, the onlay may improve the patient's vision by improving the optical performance of the patient's cornea.

[0017] When inlay and onlay corneal augmentations are in place, they may be sufficient by themselves to improve abnormal or ectatic corneal disorders. However, they may also, or instead, be the first step, followed by further reshaping of the cornea after augmentation. Further reshaping of the corneal augmentation after surgery may be, for example, surgery such as, but not limited to, photorefractive keratectomy (PRK) surgery and phototherapeutic keratectomy (PTK). [Brief description of the drawings]

[0018] [Figure 1A] FIG. 1A shows a schematic cross-sectional view of a normally functioning human eye.

[0019] [Figure 1B] FIG. 1B shows a schematic cross-sectional view of a human eye exhibiting a corneal abnormality.

[0020] [Figure 2A] FIG. 2A shows a schematic cross-sectional view of a cornea having two intrastromal cavities in preparation for having a corneal augmentation as an inlay.

[0021] [Figure 2B] FIG. 2B shows a schematic cross-sectional view of a cornea having two intrastromal cavities.

[0022] [Figure 2C] FIG. 2C shows a schematic cross-sectional view of a cornea having two intrastromal corneal augmentations as inlays.

[0023] [Figure 3A] FIG. 3A shows a schematic cross-sectional view of a cornea exhibiting keratoconus.

[0024] [Figure 3B] FIG. 3B shows a schematic cross-sectional view of a cornea prepared to receive a corneal augmentation as an onlay.

[0025] [Figure 3C]FIG. 3C shows a schematic cross-sectional view of a cornea being augmented with a corneal augmentation as an onlay.

[0026] [Figure 3D] FIG. 3D shows a schematic cross-sectional view of a cornea after epithelial tissue regrowth and augmented with a corneal onlay.

[0027] [Figure 4] FIG. 4 shows a schematic plan view of the human eye.

[0028] [Figure 5A] FIG. 5A shows a plan view of a donut-shaped corneal template.

[0029] [Figure 5B] FIG. 5B shows a plan view of two pieces cut from a donut-shaped corneal template.

[0030] [Figure 5C] FIG. 5C shows a cross-sectional view of a piece cut from a donut-shaped corneal template.

[0031] [Figure 6A] FIG. 6A shows a plan view of a tangential map of a cornea exhibiting keratoconus.

[0032] [Figure 6B] FIG. 6B shows a schematic plan view of a donut-shaped corneal augmentation positioned relative to a tangential map of a cornea exhibiting keratoconus.

[0033] [Figure 7A] FIG. 7A shows a schematic rendering of an elevation map of a cornea exhibiting keratoconus.

[0034] [Figure 7B] FIG. 7B shows a schematic cross-sectional view showing the surface of a cornea exhibiting keratoconus and a best-fit sphere as a reference.

[0035] [Figure 7C] FIG. 7C shows a schematic cross-sectional view showing the surface of a cornea exhibiting keratoconus and a highlighted best-fit sphere as a reference.

[0036] [Figure 8A] FIG. 8A shows a schematic representation of an iris image overlaid on an elevation map.

[0037] [Figure 8B] FIG. 8B shows a schematic depiction of an elevation map showing the keratoconus circle and a 3 mm representation of the pupil.

[0038] [Figure 9] FIG. 9 shows a schematic representation of a corneal augmentation that is shaped to have a planar projection that coincides with the iso-elevation lines.

[0039] [Figure 10A] FIG. 10A shows a schematic plan view of one embodiment of a corneal augmentation.

[0040] [Figure 10B] FIG. 10B shows a schematic cross-sectional view of one embodiment of a corneal augmentation.

[0041] [Figure 11] FIG. 11 shows a schematic plan view of a corneal augmentation that is shaped to avoid covering the pupil.

[0042] [Figure 12] FIG. 12 shows a schematic plan view of a corneal augmentation having a donut-shaped shape to avoid covering the pupil.

[0043] [Figure 13] FIG. 13 shows a flow diagram illustrating exemplary steps in the automated determination of the three-dimensional shape of a corneal augmentation.

[0044] [Figure 14]FIG. 14 shows a flow diagram illustrating typical steps in the automated fabrication of corneal augmentations. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] (Best Mode for Carrying Out an Invention) FIG. 1A shows a schematic cross-section 101 of a normally functioning human eye.

[0046] In a normally functioning human eye, an incoming collimated beam of light 110 may be light that is precisely focused (111) onto the retina 108 by the combined action of the lens 107 and cornea 105. The image produced on the retina 108 may then be transmitted to the brain via the optic nerve 109. The anterior cavity 106 is typically filled with a clear fluid, aqueous humor, and separates the cornea 105 from the lens 107.

[0047] FIG. 1B shows a schematic cross-section 102 of a human eye exhibiting a corneal abnormality, which may be an ectatic disorder.

[0048] Corneal ectasia may be caused by corneal thinning and subsequent distortion, which may manifest as pathologies such as, but not limited to, keratoconus, persicoid corneal degeneration, and keratoglobus. As a necessary consequence of the thinning, a cornea 112 exhibiting an ectatic disorder may be distorted away from the normal spheroid shape of a healthy cornea, thereby compromising its optical performance. For example, only a small percentage of an incoming parallel beam of light 110 may be accurately focused onto the retina 108, while the remaining portion of light 113 may not be accurately focused onto the retina.

[0049] FIG. 2A shows a schematic cross-section of a cornea exhibiting an ectatic disorder.

[0050] As shown, the cornea may exhibit keratoconus 209, in which a portion of the cornea may assume an irregular optical surface that may sometimes be referred to as a cone.

[0051] The degree or severity of keratoconus 209 may be characterized by the deviation of the cornea from an optimal optical configuration. Such an optimal optical configuration may be, for example, an ideal cornea, i.e., a portion of a spheroid, with a refractive power in the range of 30-50 diopters, with an eccentricity in the range of -2 to +2. The severity of the condition may be quantified by several clinical variables. These variables may include, for example, the following: 1: Maximum corneal curvature measurement or K-max. This can be measured as the maximum deviation of the cornea from the ideal value and can determine the severity of keratoconus. The measurement of maximum corneal curvature measurement 210 can be, for example, but not limited to, [ka] Manufactured by Pentacam TM or the like. The measurements may be quantified in diopters, or as the deviation in μm of the anterior surface of the cornea 211 from a best fit sphere 207 for the anterior surface of the cornea, or the deviation in μm of the posterior surface of the cornea 212 from a best fit sphere 208 for the posterior surface of the cornea, or a combination thereof. 2: An estimate of the corneal curvature across the visual axis. This may be obtained from refractive measurements of the degree of myopia and hyperopia caused by the remodeled cornea. Myopia may be measured assuming that the visual axis passes through the steepest part of the remodeled cornea, i.e., the cone of the keratoconus. Hyperopia may be measured by assuming that the visual axis passes through the flatter part of the remodeled cornea. Both of these refractive measurements may also be obtained using, but are not limited to, the Pentacam cornea mentioned above. TM It may also be calculated from data obtained using corneal tomography or topography, as performed by instruments such as those described above. 3: The location of the so-called cones of keratoconus, in particular the location of the cones relative to the pupil. This clinical location can be obtained by overlaying a map of the cornea onto the iris image. The map of the cornea can indicate the local focusing power of the cornea, and can be obtained using, but is not limited to, Pentacam TM The images can be acquired using instruments such as the Pentacam.TM Optical topography and tomography instruments such as typically have an iris camera that can provide a suitable iris image. 4: Diameter of the cone on the cornea. This may be obtained, for example, from an elevation map, which may compare the local height of the cornea to a reference surface, such as, but not limited to, a best-fit sphere. For example, the best-fit sphere 207 for the anterior surface of the cornea may be compared to the anterior surface of the cornea 211 to produce an elevation map. A roughly circular patch may then be evident as the boundary where the cornea begins to deviate significantly from the best-fit sphere. The diameter of the best-fit circle for this region may then be considered to be the diameter of the cone. The same calculation may be performed comparing the posterior surface of the cornea 212 to the best-fit sphere 208 for the posterior surface of the cornea.

[0052] Based on clinical measurements of the severity, location, and diameter of the keratoconus, the clinician can then determine both the best device or corneal augmentation and the best course of treatment. The device can be either a corneal inlay or onlay, and the treatment can be a multi-stage treatment, for example, where a corneal inlay or onlay is added to the cornea of ​​this patent, followed by laser reshaping of the thickened cornea.

[0053] FIG. 2B shows a schematic cross-section 202 of a cornea having two intrastromal cavities in preparation for having a corneal augmentation as an inlay.

[0054] Depending on factors such as, but not limited to, the severity and location of the lesion, a clinician may choose to treat it with a single inlay or with multiple inlays.

[0055] The intrastromal cavities 213 and 214 may be created in the corneal stroma 205 using any suitable surgical means, but the use of a femtosecond laser may be preferred because the photodissecting incisions produced by the femtosecond laser cause minimal damage to the surrounding tissue. The intrastromal cavities 213 and 214 or pockets may each create a space that is appropriately sized and shaped to receive a corneal augmentation. A typical cornea is approximately 540 μm + / - 30 μm thick, but in the case of ectasia, the thickness in the area may be as little as 300 μm. The optimal depth for locating the intrastromal cavities may be 90 μm from the epithelial tissue to at least 100 μm above the posterior surface of the cornea or Descemet's layer. Preferably, the location may be as close to the 90 μm limit as possible. There may be an entrance to the intrastromal cavities 213 and 214 that punctures the epithelial tissue 206 and allows for the insertion of the corneal augmentation.

[0056] FIG. 2C shows a schematic cross-section 202 of a cornea having two intrastromal corneal augmentations 216 and 218, which may be corneal inlays.

[0057] Corneal augmentations 216 and 218 may be said to be placed or fitted into intrastromal cavities 213 and 214, thereby strengthening and reshaping the cornea, thereby improving keratoconus. In particular, both the anterior surface of cornea 211 and the posterior surface of cornea 212 may now be matched more closely by best fit sphere 207 for the anterior surface of the cornea and best fit sphere 208 for the posterior surface of the cornea, respectively. The cornea may now more closely approximate an ideal optical configuration, thereby improving its optical performance and the patient's vision.

[0058] FIG. 3A shows a schematic cross-section 301 of a cornea exhibiting keratoconus.

[0059] 2A, the cornea may exhibit a keratoconus 209 with the maximum corneal curvature measurement 210 in the vicinity of the thinnest portion of the corneal stroma 205. The deformation of the cornea may be measured as the deviation of the anterior surface of the cornea 211 from a best fit sphere 207 for the anterior surface of the cornea. A roughly similar pattern may also be seen in the deviation of the posterior surface of the cornea 212 from a best fit sphere 208 for the posterior surface of the cornea. Both of these deviations may be measured using, but are not limited to, the Pentacam 209 described above. TM The surface area may be mapped and visualized as an elevation map using tomography or topography, using tools such as:

[0060] 3B shows a schematic cross-section 302 of a cornea prepared to receive two corneal augmentations as a corneal onlay. The first surgical step in the onlay procedure may be to remove one or more regions 305 and 310 of epithelial tissue 206. This removal may be performed by any suitable surgical technique, but the use of a femtosecond laser may be preferred because the photodissecting incisions produced by the femtosecond laser cause minimal damage to the surrounding tissue. The regions 305 and 310 in which the epithelial tissue is removed may typically be on either side of the thinnest portion of the corneal stroma 205.

[0061] In addition to removing the epithelial tissue, a surface chamfer 306 may be produced on the periphery of the area of ​​removed epithelial tissue. This may also be done using a femtosecond laser and may play a role in aiding in anchoring the onlay corneal augmentation.

[0062] FIG. 3C shows a schematic cross-section 303 of a cornea augmented with two corneal augmentations 308 and 311, which may be corneal onlays.

[0063] Corneal augmentations 308 and 311 may be corneal onlays that may be placed or onlaid over the area in which epithelial tissue has been removed. The corneal augmentation may be temporarily held in place by tucking its outer periphery under surface chamfer 306 on the periphery of the area of ​​removed epithelial tissue. The corneal augmentation may also or instead be temporarily held in place by surgical adhesive, or sutures, or a combination thereof.

[0064] FIG. 3D shows a schematic cross-section 304 of a cornea after regrowth of epithelial tissue 309 and augmented with two corneal onlays.

[0065] Regrowth of the epithelial tissue may take approximately several days to a week. During this period, the patient may wear surgical contact lenses to protect the augmentation. As the epithelial tissue regrows, the corneal augmentation 308 may integrate with the corneal stroma 205, thereby strengthening and reshaping the cornea. In particular, both the anterior surface of the cornea 211 and the posterior surface of the cornea 212 may now be matched more closely by the best fit sphere 207 for the anterior surface of the cornea and the best fit sphere 208 for the posterior surface of the cornea, respectively. The cornea may now more closely approximate an ideal optical configuration, thereby improving keratoconus. This may also improve the optical performance of the cornea and the patient's visual acuity.

[0066] Although the procedures detailed in Figures 2A-C and 3A-D are shown as having two corneal augmentations, respectively, there are many opportunities where a single, appropriately shaped and placed corneal augmentation may prove effective, or even more effective, in correcting corneal abnormalities.

[0067] The procedures detailed in Figures 2A-C and 3A-D, i.e., augmentation with corneal inlays and corneal onlays, may be sufficient in themselves to improve abnormal or ectatic corneal disorders. However, they may also, or instead, be the first step, followed by further shaping of the corneal augmentation after augmentation. Further shaping of the corneal augmentation after augmentation may be a procedure, such as, for example, but not limited to, photorefractive keratectomy (PRK) or phototherapeutic keratectomy (PTK). Such a procedure may be accomplished using a suitable laser, such as, for example, but not limited to, a femtosecond laser, or an excimer laser, or a combination thereof.

[0068] 4 shows a schematic plan view 401 of the human eye. As shown, the eye typically consists of an eyeball 407 contained within a protective orbit and surrounded by eyelashes 408. Components of the eye involved in the imaging function of the eye include the iris 406 and the pupil 405. The pupil 405 is a variable opening through which, for example, light rays pass to be imaged onto the retina at the back of the eye.

[0069] FIG. 5A shows a plan view 501 of a donut-shaped corneal template.

[0070] The initial corneal template may have been obtained from any suitable material, such as, but not limited to, a corneal autograft, a corneal allograft, a corneal xenograft, manufactured corneal tissue, or some combination thereof, prior to being molded into a donut shape. In a preferred embodiment, the corneal template may be obtained from a donated human cornea, such as, for example, but not limited to, prepared and / or stored by a reputable eye bank, such as, but not limited to, CorneaGen Inc., a subsidiary of SightLife, Inc., also headquartered in Seattle, Washington.

[0071] Such eye banks typically include, but are not limited to: Improve the biocompatibility of corneal templates by decellularization. Assist in preserving the corneal template by decontamination and sterilization; Detachment agents maintain the clarity of the corneal template and minimize edema; The addition of a sclerosing agent increases the biomechanical strength of the corneal template. Improve the ease of performing the augmentation procedure by markings for orientation and by suitable staining for visibility; Allowing the corneal template and the corneal augmentation obtained therefrom to be kept at room temperature for a reasonable length of time, typically up to two years; and Improving post-operative healing and prevention through soaking in drugs, biological medicines, or regenerative therapies The corneal template is used for multiple purposes such as:

[0072] The initial corneal template may then be shaped into a donut or ring shape having a circular outer radius 505 and a circular inner radius 506. This shaping may be done using, for example, a femtosecond or excimer laser. The donut or ring shape may have one or more side cuts 507, which may be accomplished using a femtosecond laser. These side cuts may result in a corneal piece having the required arc length 508.

[0073] Outer radius 505 may be, for example, in the range of 7-9 mm, and more preferably is about 8 mm. Inner radius 506 of the donut-shaped corneal template may be in the range of 3-5 mm, and more preferably is about 4 mm.

[0074] FIG. 5B shows a plan view 502 of two pieces 509 and 510 cut from a donut-shaped corneal template. Once trimmed to the appropriate thickness, these pieces can be suitable corneal augmentations. They may be used singly or in combination. Although FIG. 5B shows two pieces being cut from a donut, a single arc-shaped piece having an arc length greater than 180 degrees may instead be obtained from the donut.

[0075] 5C shows a cross-section 503 of a piece cut from the donut-shaped corneal template. Once trimmed to the appropriate thickness, this piece can now become a suitable corneal augmentation.

[0076] A typical width 512 of a donut sector shaped corneal augmentation may be in the range of 3-5 mm, more preferably about 4 mm.

[0077] The thickness 511 of the donut sector shaped corneal augmentation may depend on the severity of the corneal abnormality. The thickness 511 of the corneal augmentation may be proportional to, for example, the maximum keratometric curvature measurement, a.k.a. K-max, of the abnormality.

[0078] For example, a satisfactory relationship between maximum corneal augmentation thickness and K-max has been determined through experience and is presented in Table 1. [Table 1]

[0079] The values ​​in Table 1 can be approximated by the following equations: t=10×K-max-300 ... (1) where t represents the maximum thickness in μm and K-max represents the maximum keratometric curvature in diopters.

[0080] FIG. 6A shows a plan view 601 of a tangential map of a cornea exhibiting keratoconus.

[0081] Not limited to, Pentacam TM Data obtained when examining an eye using a tomography or topography system such as may be displayed in a number of ways, including, but not limited to, pachymetric maps, which display the corneal thickness; axial and tangential maps, which display the local curvature of the cornea; and elevation maps, which display the corneal surface relative to a reference surface.

[0082] The tangential map is typically displayed in false color, with a particular color representing a particular local refractive power. For example, the increased power isodiopter line 605 may be displayed in warmer colors toward the red end of the spectrum, while the decreased power isodiopter line 606 may be displayed in cooler colors toward the blue end of the spectrum. The maximum corneal curvature measurement 210 may thus be displayed as a dark red color. A typical tangential map may be overlaid with a 3 mm circle 608 that fills the corneal circumference 607 and represents the pupil of the eye.

[0083] FIG. 6B shows a schematic plan view 602 of two donut-shaped corneal augmentations positioned relative to a tangential map of a cornea exhibiting keratoconus.

[0084] 6B, the first corneal augmentation 609 may be located on one side of the maximum corneal curvature measurement 210. The first corneal augmentation 609 may further be located such that the outer edge may be best fit to a first isodiopter line 610 of partially elevated power, while the inner edge may be best fit to a second isodiopter line 611 of elevated power. The arc length of the first corneal augmentation 609 may also be constrained by the isodiopter lines.

[0085] The second corneal augmentation 612 may be located on the other side of the maximum corneal curvature measurement 210 if deemed necessary for amelioration of the corneal disorder. The second corneal augmentation 612 may further be located such that the outer edge may best fit against a first isodiopter line of partially reduced power 613, while the inner edge may best fit against a second isodiopter line of partially reduced power 614. The arc length of the second corneal augmentation 609 may also be constrained by the isodiopter lines.

[0086] FIG. 7A shows a schematic rendering of an elevation map 701 of a cornea exhibiting keratoconus.

[0087] Not limited to, Pentacam TM Data obtained when examining an eye using a tomography or topography system such as may be displayed in a number of ways, including, but not limited to, pachymetric maps, which display the corneal thickness; axial and tangential maps, which display the local curvature of the cornea; and elevation maps, which display the corneal surface relative to a reference surface.

[0088] Elevation maps are typically displayed in false color, with a particular color representing a particular amount of deviation of the corneal surface from the reference surface. To comply with patent office drawing requirements, elevation map 701 is shown with dotted lines representing iso-elevation lines, i.e., lines that would normally be displayed as particular colors. For example, iso-elevation line 706 represents a particular amount of elevation of the corneal surface above the reference surface, and by convention would normally be displayed with warm colors that tend toward the red end of the spectrum. Iso-elevation line 707 represents elevation of the corneal surface below the reference surface, and would normally be displayed with cool colors that tend toward the blue end of the spectrum. Zero iso-elevation line 705 would normally be displayed as a color within the yellow to green portion of the spectrum.

[0089] The numbers 0, 90, 180, and 270 represent orientations in degrees, following ophthalmological convention.

[0090] FIG. 7B shows a schematic cross-section 502 showing the surface of a cornea exhibiting keratoconus 710 and a best fit sphere 709 as a reference.

[0091] Cross section 702 is taken on line "BB" in FIG. 7A. Best fit sphere 709 is a best fit sphere for the entire corneal surface 708, which may include data points from the region of keratoconus 710. The elevation map shown in FIG. 7A may represent the difference between the best fit sphere 709 and one of the surfaces of the cornea. As a point of reference, in a normal eye, the anterior elevation is typically in the range of 1.63 + / - 1.4 μm. In a patient with keratoconus, the anterior elevation may be in the range of 20.9 + / - 21.9 μm. The best fit sphere typically has a radius in the range of 6.5 + / - 2 mm.

[0092] FIG. 7C shows a schematic cross-section 703 showing the surface of a cornea exhibiting keratoconus 710 and a highlighted best fit sphere 711 as a reference surface.

[0093] The highlighted best fit sphere 711 is calculated using data from the corneal surface 708 , but may exclude data from region 712 , which may represent the area most affected by keratoconus 710 .

[0094] FIG. 8A shows a schematic representation 801 of the iris image 406 overlaid on an elevation map.

[0095] By overlaying an image of the iris 406 onto the elevation map, it may be possible to determine the relative positions of the pupil 405 and the circle 806 that defines the diameter of the keratoconus. Also shown are other iso-elevation lines 805.

[0096] 8B shows a schematic representation 802 of an elevation map with iso-elevation lines 805. Also shown is a keratoconus circle 806, and a 3 mm circle 807 that may represent the position of the pupil. The circle 806 that defines the diameter of the keratoconus may be, for example, a best-fit circle for the iso-elevation lines where the surface of the cornea begins to deviate significantly from the best-fit sphere. The diameter of the best-fit circle may be considered to be the diameter of the cone of the keratoconus.

[0097] Also shown is a vector 810 that represents the distance and direction between the center of the pupil and the center of the keratoconus maximum 808 .

[0098] 9 shows a schematic representation 901 of a corneal augmentation 905 that is shaped to have a planar projection that matches the iso-elevation lines 805 of the corneal elevation map. The corneal augmentation 905 may be approximately centered over the keratoconus maximum 808.

[0099] Selection of an appropriate iso-elevation line may define the peripheral shape of the planar projection of the corneal augmentation 905, the maximum thickness of which may be determined by the severity of keratoconus as measured by the value of the keratoconus maximum, also known as K-max.

[0100] For example, a satisfactory relationship between maximum thickness of the corneal augmentation and K-max has been found through experience and is represented in Table 1 shown above, and can be approximated by Equation 1 shown above.

[0101] FIG. 10A shows a schematic plan view 1001 of the corneal augmentation 905.

[0102] While the corneal augmentation 905 shown in the figure has a planar projection that matches the iso-elevation lines of the corneal elevation map, one skilled in the art will appreciate that the planar projection may be any suitable planar projection such as, without limitation, a polygon that may be best fitted in part to the iso-elevation lines, a lens shape that may be best fitted in part to the iso-elevation lines, a circle that may be best fitted in part to the iso-elevation lines, a freeform curve that may be best fitted in part to the iso-elevation lines, a crescent shape that may be best fitted in part to the iso-elevation lines, or some combination thereof.

[0103] The corneal augmentation 905 may be said to have been generated from a corneal template and then converted into a suitable three-dimensional shape using any suitable material removal or cutting technique, such as, but not limited to, a computer-guided femtosecond laser, or a computer-guided excimer laser, or some combination thereof.

[0104] The corneal template may be obtained of any suitable material, as discussed in more detail above.

[0105] FIG. 10A also shows a corneal augmentation 905 marked with a placement mark. The markings can be, for example, small holes drilled in the corneal augmentation and arranged to provide both positioning and orientation information. For example, a first placement mark 1005 marking a 90 degree alignment can have three small holes, indicating a vertically upward placement. A second placement mark 1006 marking a 270 degree alignment can have only a single hole, indicating a vertically downward placement. When an imaginary line is drawn from the first mark to the second, the main line can pass through the center of a 3 mm diameter circle 807, representing the pupil. In actual placement, when correctly placed, the imaginary line can pass through the center of the patient's pupil. Similarly, a third placement mark 1008 marking a 180 degree alignment can have two holes, while a fourth placement mark 1007 marking a 0 degree alignment can have a single hole. When an imaginary line is drawn from the third placement mark to the fourth, this will pass horizontally through the center of the pupil when the enhancer is correctly positioned and oriented.

[0106] Those skilled in the art will appreciate that although the installation markings have been described in terms of drilled holes, any suitable marking system may be used, including, but not limited to, colored dyes, small incisions, or some combination thereof.

[0107] 10B shows a schematic cross-sectional view 1002 of a corneal augmentation 905. As shown, the corneal augmentation 905 has a crescent shaped cross-section with a maximum thickness 1009, which may be proportional to the maximum corneal curvature measurement or K-max, which may be determined by Equation 1 or Table 1. If the corneal augmentation 905 is intended for use as an onlay, the posterior surface 1010 may be shaped to match the anterior surface of the cornea in the area where the onlay augmentation is intended to be placed.

[0108] Although the cross section of the reinforcement is shown as a crescent shape, one skilled in the art will recognize that it may be of any suitable shape, such as, but not limited to, a rectangle, an oval, a sphere, a portion of a sphere, or some combination thereof.

[0109] FIG. 11 shows a schematic plan view 1101 of a corneal augmentation 1105 that is shaped to avoid covering the pupil.

[0110] A planar projection of a corneal augmentation 1105, shaped to avoid covering the pupil, may have a portion of the periphery 1106 that may conform to the iso-elevation line 805, and a portion of the periphery 1107 relative to a 3 mm diameter circle 807 that represents the position of the pupil. A reason for making such an augmentation may be to avoid the augmentation blocking the patient's line of sight, as the surface of the augmentation may not be smooth enough and may adversely affect the patient's vision.

[0111] Although the planar projection of the augmentation shown in FIG. 11 is depicted as being a partial best fit to the iso-elevation lines and a partial best fit to a circle, one skilled in the art will appreciate that the planar projection can be any suitable shape, such as, but not limited to, a crescent, or a circular arc, or a freeform curve, or some combination thereof, which may also be a partial best fit to the iso-elevation lines and / or to a circle representing the pupil.

[0112] FIG. 12 shows a schematic plan view 1201 of a corneal augmentation 1205 having a donut-shaped shape to avoid covering the pupil.

[0113] The purpose of the cut may be to avoid obscuring the line of sight through the cornea because the surface of the augmentation may not be smooth enough to ensure sufficiently unperturbed light transmission.

[0114] The outer periphery of the planar projection of the corneal augmentation 1205, which has a doughnut-shaped shape to avoid covering the pupil, can be a freeform shape that is a best fit to the iso-elevation lines, or it can be any suitable geometric shape, such as, but not limited to, a polygon or a circle, which can also be a best fit to the partially selected iso-elevation lines. The corneal augmentation can also have a cutout 1206 that is shaped and sized to avoid obscuring the pupil, as represented by the 3 mm diameter 807. The planar projection of this cutout can be a circle that encompasses the 3 mm diameter circle 807, or it can be a best fit to it. One skilled in the art can understand that the planar projection of the cutout can also be any suitable freeform shape, or polygon, or combination thereof, that encompasses or can be a best fit to the 3 mm diameter circle 807 that represents the pupil.

[0115] FIG. 13 shows a flow diagram 1301 illustrating exemplary steps in the automated determination of the three-dimensional shape of a corneal augmentation.

[0116] In step 1301, “Topography and Tomography Assessment”, the patient's cornea is examined using a method such as, but not limited to, a Pentacam. TM The imaging device may be inspected using a suitable computer-controlled topography or tomography tool such as a CT scanner.

[0117] In step 1302 "Determine Optical 3D Shape", a suitably programmed digital processor may take the data acquired in the previous steps and calculate an optimal three-dimensional shape for the corneal augmentation to improve the patient's corneal abnormality. This calculation may include some or all of the concepts discussed above, such as, but not limited to, the relationship between the maximum corneal curvature measurement and the preferred thickness of the augmentation, and best fitting the periphery of the augmentation to one or more iso-deviation or iso-power lines, partially in elevation. This calculation may also take into account other data that may be provided, such as, but not limited to, the properties of the patient's other eye or cornea.

[0118] In step 1303 "Generate and export cutting files," a suitably programmed digital processor can convert the optimum three-dimensional shape into a form suitable for use by a computer-controlled micro-precision forming machine. This can result in a cutting file formatted in a suitable CAD format. Suitable CAD format file types include, but are not limited to, the well-known STEP and STL file formats.

[0119] FIG. 14 shows a flow diagram 1401 illustrating exemplary steps in the automated fabrication of a corneal augmentation.

[0120] In step 1401 "Get Cut File", the CAD cut file generated in the process described above may be input into a suitable computer controlled fine precision molding machine. The fine precision molding machine may include a femtosecond laser and a computer controlled fine precision XYZ stage. Such a stage may be constructed from components supplied by Thorlabs of Newton, NJ. The components may include, for example, their MLS203-1-high speed XY scanning stage and their MZS500-EZ axis piezo stage.

[0121] In step 1402 "Machine Optical 3D Shape," a corneal template mounted on a computer-controlled fine precision XYZ stage may be translated past the focus of a suitably powerful femtosecond laser to produce a corneal augmentation. This process may be similar to 3D printing in reverse, i.e., successive layers of material may be removed instead of added.

[0122] Those skilled in the art will appreciate that although the present invention has been described primarily with respect to keratoconus, the methods of the present invention may be used or adapted for use with a variety of other corneal ectasias, including, but not limited to, keratoglobus, Persian corneal degeneration, posterior keratoconus, post-LASIK ectasia, Therrien peripheral keratoconus, and irregular astigmatism.

[0123] Those skilled in the art will further appreciate that although the present invention has been described primarily through reference to elevation maps, the steps of the present invention may also, or instead, be implemented through the use of other corneal maps, such as, but not limited to, pachymetric maps, which indicate corneal thickness, and axial and tangential maps, which indicate the local curvature of the cornea.

[0124] (Industrial Availability) The present invention may have applicability in the field of optical devices and in the field of corrective eye surgery.

Claims

1. 1. A system for ameliorating corneal abnormalities, comprising:

1. A topography or tomography instrument comprising: determining a measure of the severity of the abnormality of the cornea; and generating a corneal map of the cornea quantifying deviations of the abnormal cornea from an optimal corneal shape; a topography or tomography instrument configured to perform 1. A processor comprising: Using the corneal map and the severity scale to calculate an appropriate three-dimensional shape of a corneal augmentation to ameliorate the corneal defect. A processor configured to: A molding machine comprising: producing said corneal augmentation using a corneal template comprised of corneal tissue and having said appropriate three-dimensional shape; a molding machine configured to Equipped with The system, wherein the corneal augmentation is used to augment the cornea.

2. The corneal template is obtained from a source other than the cornea being treated with one of a corneal allograft and a corneal xenograft; The system of claim 1 , wherein prior to augmentation, the molding machine molds the corneal template to generate the appropriate three-dimensional shape of the corneal augmentation.

3. 3. The system of claim 2, wherein the abnormality of the cornea is keratoconus, the measure of severity is a maximum keratometric curvature (K-max), and the corneal map is obtained using corneal tomography or corneal topography.

4. 4. The system of claim 3, wherein the appropriate three-dimensional shape is a sector cut from a donut-shaped shape having an inner radius in the range of 3-5 mm, an outer radius in the range of 7-9 mm, and a uniform thickness, the uniform thickness being determined using the equation: t=10×K-max-300, where t is the thickness in μm and K-max is the maximum corneal curvature measurement measured in diopters.

5. The system of claim 3 , wherein the corneal map is an elevation map, and the approximate three-dimensional shape of the corneal augmentation has a planar projection that is a curve that is a best fit in part to the iso-elevation lines of the elevation map.

6. 4. The system of claim 3, wherein the maximum thickness of the corneal augmentation is proportional to the maximum keratometric measurement of the keratoconus and is determined using the equation: t=10×K-max-300, where t represents the maximum thickness in μm and K-max represents the maximum keratometric measurement measured in diopters.

7. The system described in claim 3, wherein the processor is a suitably programmed digital processor configured to automatically determine the appropriate three-dimensional shape using data comprising the corneal map and the severity scale, and a cutting file is generated by the suitably programmed digital processor, the cutting file containing instructions readable by a computer-controlled femtosecond laser to form the corneal augmentation.

8. 4. The system of claim 3, wherein the corneal map is an elevation map, and the approximate three-dimensional shape of the corneal augmentation has a planar projection that is one of a polygon, a lens, a donut, a crescent, and an arc, and the planar projection is a best fit in part to an iso-elevation line of the elevation map.

9. 3. The system of claim 2, wherein the corneal augmentation is an inlay, and the system further comprises a femtosecond laser configured to create an intrastromal cavity, the cavity sized and shaped to accommodate the inlay.

10. 3. The system of claim 2, wherein the corneal augmentation is an onlay placed external to the cornea being treated, and the system further comprises a femtosecond laser configured to remove a continuous region of epithelial tissue that corresponds in area units to a planar projection of the corneal augmentation.

11. The system described in claim 10, wherein the onlay is temporarily retained on the cornea using a surface chamfer of epithelial tissue on the periphery of the removed area of ​​epithelial tissue.

12. The system of claim 2, further comprising an excimer laser configured to perform photorefractive keratectomy (PRK) surgery for post-augmentation reshaping of the cornea.

13. A device for improving corneal abnormalities, comprising: Equipped with corneal augmentation, said corneal augmentation having a suitable three-dimensional shape characterized in that said corneal augmentation is machined from a corneal template comprised of corneal tissue; The suitable three-dimensional shape is determining a measure of the severity of the abnormality of the cornea; and generating a corneal map of the cornea quantifying deviations of the abnormal cornea from an optimal corneal shape; calculating the appropriate three-dimensional shape of the corneal augmentation using the corneal map and the severity measure to ameliorate the corneal defect; A device, the device being determined by a method comprising:

14. The device of claim 13 , wherein the corneal template is one of a corneal allograft and a corneal xenograft.

15. 14. The device of claim 13, wherein the corneal augmentation is an inlay, the inlay intended for insertion into a suitably shaped and sized intrastromal cavity in the cornea to be treated.

16. 14. The device of claim 13, wherein the corneal augmentation is an onlay, the onlay intended to be placed on the exterior of the cornea over an area of ​​the cornea to be treated, and a continuous area of ​​epithelial tissue corresponding in size area units to a planar projection of the corneal augmentation is first removed from the area of ​​the cornea.

17. 17. The device of claim 15 or 16, wherein the abnormality of the cornea is keratoconus, the measure of severity is a maximum keratometric curvature (K-max), and the corneal map is obtained using corneal tomography or corneal topography.

18. 16. The device of claim 15, wherein the appropriate three-dimensional shape is a sector cut from a donut-shaped shape having an inner radius in the range of 3-5 mm, an outer radius in the range of 7-9 mm, and a uniform thickness, the uniform thickness being determined using the equation: t=10×K-max-300, where t is the thickness in μm and K-max is the maximum corneal curvature measurement measured in diopters.

19. 17. The device of claim 15 or 16, wherein the maximum thickness of the corneal augmentation is proportional to the maximum keratometric curvature of the keratoconus and is determined using the equation: t=10×K-max-300, where t represents the maximum thickness in μm and K-max represents the maximum keratometric curvature measured in diopters.

20. The device of claim 15 or 16, wherein the appropriate three-dimensional shape is automatically determined by a suitably programmed digital processor using data comprising the corneal map and the severity scale, and a cutting file is generated by the suitably programmed digital processor, the cutting file containing instructions readable by a computer-controlled femtosecond laser to form the corneal augmentation.

21. 17. The device of claim 15 or 16, wherein the corneal map is an elevation map and the suitable three-dimensional shape of the corneal augmentation has a planar projection that is one of a polygon, a lens, a donut, a crescent, and an arc, and the planar projection is a best fit in part to the iso-elevation lines of the elevation map.

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